History of anorexia nervosa in bulimic patients: its influence on body composition

To analyze the body composition of a group of patients fulfilling DSM-IV criteria for bulimia nervosa (BN), comparing the patients who had a history of DSM-IV anorexia nervosa (AN) with those without such a history to determine (1) whether both groups differed in terms of body composition and (2) whether the differences between groups could be the consequence of the past condition.

The sample consisted of 104 patients, 43 with prior AN (BN-AN group) and 61 without a history of AN (BN-nonAN). The patients were assessed using anthropometric and bioelectrical methods: height and weight, body circumferences, abdominal diameter, skinfold thickness, and body impedance analysis. In a later phase and to test the influence of current low weight on the results, two experimental groups were created: the first group was composed of the patients from the BN-AN group who had a normal body mass index (BMI range in this group, 20.1-23.4 kg/m2; n = 23); the second group consisted of 23 patients from the BN-nonAN group in the same BMI range. In both phases unpaired sample t tests were performed for statistical analysis.

More than 40% of the bulimic patients with a history of AN had a BMI less than 20. They had a lower percentage of body fat, lower muscle mass, and higher percentage of extracellular water. Nevertheless, most of these differences disappeared in the second phase of the analysis, when only the patients within a normal weight range were compared.

According to these results, a significant number of bulimic patients with a history of AN tend to retain some clinical traits of the past condition and could be viewed as remaining in a "subclinical anorexic status": they are thinner and seem to have less difficulties in maintaining low weight than patients without a history of AN. Nevertheless, in patients who have reached a normal weight after AN, all these differences disappear. This fact raises some important questions related to the boundaries between AN and BN, the shifting from one to another, or when AN patients really recover.